Lectins, which are proteins capable of interacting with certain macromolecules and/or cell types via specific sugar moieties, are being used to investigate the interactions between saliva and oral bacteria in order to better elucidate the role these interactions play in plaque and caries development. Findings to date support the conclusion that one lectin, wheat germ agglutinin, can reversibly bind to and inhibit the aggregating factor in saliva that is responsible for inducing the aggregation of Streptococcus mutans cells. These results provide evidence that the salivary aggregating factor contains N-acetylglucosamine. Other lectins with different sugar specificities are currently being employed in an effort to further define the sugar moieties present in the aggregating factor. Animal studies with wheat germ agglutinin or similar reacting lectins are contemplated in order to see what effect the inhibition of saliva-induced bacterial aggregation will have on in vivo plaque development.